Reverend, there have been a couple of shader modifications for Doom3 now (first the Humus mod, rolled into ATi's driver, now Tertsi's mod).

Have you ever discussed such mods with JC in your discussions with him? I (amongst many others I suspect) would be interested in hearing JC's opinion, especially with regard to pure shader math vs texture lookup + shader math (Tertsi's mod can do both).

Like what was mentioned above, deleting the file should work, but also, where you choose Ultra quality, etc. there is a "defaults" option. I thought that would put things back to the defaults.

You mean in the in-game menu? Nope. Changing that sets the doom3config.cfg to default for display settings. This mod doesn't alter the config files, it overrieds the base shader file, two different things.

Might be, specular lookup from texture is worse than math, but then again math gives other results than Carmack intended if I understand correctly.
Normalizing via NV40 instruction set is not exactly same as standart shader path, as it's carried out in lower precision, but then again standart path used cubemaps for normalizations I think...
Swizzling, have no impact on quality.
If I understand correctly RFL_SAT can be unchecked if you use tex lookups, as it just avoids plastic looks if you use math...

Generally speaking, and I honestly do not want anyone to read this as taking anything away from the author of this "app" (there's a reason why this thread exists in this particular forum!), John tried to make almost everything look the same for the majority of the cards when using the ARB2 (default) path.

The point is John wanted lots of folks to see Doom3 the same way no matter the host video card. If the only card that exists right now is one based on NV3x or NV4x, the author of this "app" wouldn't probably have had so many enjoyable hours experimenting with things, since John probably wouldn'tve afforded him the opportunity . Most of the performance-related options offered by this app wouldn't even exist! The other (quite significant, judging from the responses here) "Wow" changes the author of this "app" offers are simply a matter of difference in artistic taste between him (the author of this app, I mean) and id Software, i.e. the specular degree.

Remember what John wrote me more than half a year ago (well, I posted it at the Beyond3D forums anyway, so you may not "remember" ) :

Quote:

Originally Posted by John Carmack, to Reverend, via email

The specular function in Doom isn't a power function, it is a series of clamped biases and squares that looks something like a power function, which is all that could be done on earlier hardware without fragment programs. Because all the artwork and levels had been done with that particular function, we thought it best to mimic it exactly when we got fragment program capable hardware. If I had known how much longer Doom was going to take to ship from that time, I might have considered differently.

It should be noted that a power function is a strictly empirical approximation of a surface's specular response, so other specular approximations shouldn't be looked at as just approximating a power function. For instance, especially for broad highlights, it is nice to have a finite cutoff angle, rather than the power limit approach.

The lookup table is constant in Doom, so there isn't any real strong argument against replacing it with code. The lookup table was faster than doing the exact sequence of math ops that the table encodes, but I can certainly believe that a single power function is faster than the table lookup.

That said, the parallax mapping work (as shown via the author's screenshots) is interesting and ALWAYS welcomed in any game.

I hope those driver engineers at NVIDIA don't read his shaders and do some "optimizations" (really, I'm joking!)

Reverend, there have been a couple of shader modifications for Doom3 now (first the Humus mod, rolled into ATi's driver, now Tertsi's mod).

Have you ever discussed such mods with JC in your discussions with him? I (amongst many others I suspect) would be interested in hearing JC's opinion, especially with regard to pure shader math vs texture lookup + shader math (Tertsi's mod can do both).

Read my previous post.

That response by John to me was related to Humus' hack, although it wasn't his first response (his response, as quoted above by me, was about my second question -- related to Humus's work -- to him about lookups for different materials).

Like I said, there's a reason why this thread exists in this particular forum. And that's why every single one of John's work inspires folks to experiment. Because he lets us, not because he didn't think of it. Again, I hope no one reads this as taking anything away from the author of this app. This sort of mod/hack is fun, correct?

Oh yes, definitely fun, and JC's engines have always been wonderful for modding and learning.

You have to wonder though if JC would have preferred math to lookup originally if not for the GF4 MX, which is really a card nVidia shouldn't be proud of and has probably held a lot of graphical advances back due to the numbers it has sold in.

You have to wonder though if JC would have preferred math to lookup originally if not for the GF4 MX, which is really a card nVidia shouldn't be proud of and has probably held a lot of graphical advances back due to the numbers it has sold in.

I can't speak for John but I'd guess that the GF4MX is a consideration; read his last paragraph in his email to me. The two sentences there sound kinda contradictory but it seemed quite obvious to me what he meant.

Going further along this line would appear to be taking this thread off-topic, so let's stop here about this and start elsewhere if you'd like to discuss. No guarantees though as I have cut back a lot on this hobby of mine.

You mean in the in-game menu? Nope. Changing that sets the doom3config.cfg to default for display settings. This mod doesn't alter the config files, it overrieds the base shader file, two different things.

Actually, I meant the specular mode option that is part of the tweaker. It has an option for defaults but on second thought, I doubt it returns everything to normal. Probably just that setting or maybe the defaults for the mod.